1. Field of the Invention
The present invention relates in general to power seat slide devices for motor vehicles, and more particularly to power seat slide devices of a type which generally comprises a stationary rail fixed to a vehicle floor, a movable rail movable on the stationary rail and carrying thereon a seat, a gear member held by one of the stationary and movable rails, a counter member of the gear member held by the other of the stationary and movable rails and engaged with the screw shaft, and an electric motor for driving or turning either one of the gear member shaft and the counter member.
2. Description of the Prior Art
Hitherto, various power seat slide devices for motor vehicles have been proposed and put into practical use. One of the conventional devices is described in Japanese Utility Model First Provisional Publication 1-99734.
Some of the devices are of a type which generally comprises a stationary rail fixed to a vehicle floor, a movable rail movable on the stationary rail and carrying thereon a seat, a screw shaft held by one of the stationary and movable rails, a nut held by the other of the stationary and movable rails and engaged with the screw shaft, and an electric motor for driving or turning either one of the screw shaft and the nut. A wire harness extends between the electric motor and an electric power source. Upon energization of the electric motor, relative displacement between the screw shaft and the nut changes causing movement of the movable rail relative to the stationary rail. With this, the seat is moved to a new fore-and-aft position relative to the vehicle floor.
However, due to inherent construction, the power seat slide devices of the above-mentioned type tend to have the following drawbacks.
First, due to usage of a lengthy screw shaft, it is difficult to provide the power seat slide device with a compact construction. Furthermore, due to the same reason, mounting of the screw shaft to the stationary or movable rail is troublesome and thus takes a greater assembly time, resulting in greater cost. In fact, it is difficult or at least troublesome to properly engage the screw shaft with the nut. That is, the screw shaft should be accurately arranged in parallel with the movable or stationary rail to which the nut is secured. If such parallel arrangement is not properly made, smoothed movement of the movable rail relative to the stationary rail is not achieved. Although this drawback may be solved when the length of the screw shaft is reduced, the moving range of the seat becomes limited correspondingly.
Second, the wire harness of the electric motor is lengthy. The lengthy wire harness tends to produce an unsightly loosened portion when the seat comes to one of frontmost and rearmost positions. The loosed portion has such an undesirable possibility as to abruptly catch the foot of a passenger who is willing to take or leave the seat.